vagabond

Apparently, this glowing blue cloud was observed after sunset the other night in Seattle. Wish I could have seen it; it's pretty.

Excerpt from the news article: "science has an explanation -- they're called "noctilucent" clouds, and they're some of the highest clouds in Earth's atmosphere, hanging out about 50 miles above the Earth's surface -- that's over 260,000 feet! (Most of our highest clouds, like the common cirrus cloud, are usually between 30,000-35,000 feet.)

These noctilucent clouds are made of tiny ice crystals and are most commonly seen in the higher latitudes (between 50-70 degrees; Seattle is at 47ish, so not too out of the realm) during the summer months."

multipilot

That's pretty cool. I learn something new everyday on these forums.

Ftrooppilot

A further explanation from Wikpedia:

Noctilucent clouds, also known as polar mesospheric clouds, are bright cloudlike atmospheric phenomena visible in a deep twilight. The name means roughly "night shining" in Latin. They are most commonly observed in the summer months at latitudes between 50° and 70° north and south of the equator.
They are the highest clouds in the Earth's atmosphere, located in the mesosphere at altitudes of around 85 km, and are visible only when illuminated by sunlight from below the horizon while the ground and lower layers of the atmosphere are in the Earth's shadow; otherwise they are too faint to be seen. Noctilucent clouds are not fully understood meteorological phenomena. Clouds generally are not able to reach such high altitudes, especially under such thin air pressures.

Unfortunately I don't have my detailed photos from home. (Out cruising). Found a household inventory photo in the computer with a wall group. If you notice the "horizon" shot, it's one of noctilucent clouds taken from a RB-57F near 70,000 feet.